Abstract
Abstract A correction of CTOD for constraint loss in large-scale yielding conditions is made on the basis of the Weibull stress fracture criterion that eliminates an excessive conservatism in the conventional fracture assessment and material fracture toughness requirement. A CTOD ratio β = δ3P / δWP (<1) is proposed, where δWP is the CTOD of a wide plate component and δ3P is an equivalent CTOD of the fracture toughness specimen at which the toughness specimen gives a compatible Weibull stress with the wide plate. The CTOD ratio β is decreased to a large extent after full yielding of the wide plate component, which is more significant for a high yield ratio YR and a deep surface crack in the wide plate. The Weibull modulus m exerts a marginal influence on β. A case study is presented on the application of the CTOD ratio β to the fracture performance assessment of full-scale column-to-beam connections subjected to cyclic and dynamic loading.
Highlights
The fracture mechanics approach to structural design and material selection relies on the stress intensity factor K, crack tip opening displacement (CTOD, δ) and J integral as the controlling parameters for stress fields ahead of a crack
In order to overcome limitations of the toughness scaling model (TSM), a modified toughness scaling with the Weibull stress was developed [7, 8], which requires the attainment of a specified Weibull stress to cause cleavage fracture at the same probability in different specimen geometry
This paper presented the CTOD toughness scaling between structural components and fracture toughness specimens
Summary
The fracture mechanics approach to structural design and material selection relies on the stress intensity factor K, crack tip opening displacement (CTOD, δ) and J integral as the controlling parameters for stress fields ahead of a crack. In large-scale yielding conditions, the actual stress fields deviate from the K- and Jcontrolled fields and depend significantly on the crack size and geometry of specimens employed This is due to the constraint effect on the crack-tip plasticity. A loss of constraint resulting from large-scale yielding relaxes the stress elevation for notched-tension panels and shallow-notch specimens, while deep-notch bend and compact specimens maintain a high level of crack tip constraint. Such constraint loss leads to an apparently increased fracture resistance Kc , δc and Jc for the former configurations. The CTOD values were calculated according to BS7448 for the compact and deep-notch bend
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
